/**
 * Created by Administrator on 2016/4/2.
 */
import java.util.*;
public class Average2{
    public static void main(String[] args){
        try{
            Scanner console=new Scanner(System.in);
            double sum=0;
            int count=0;
            while(true){
                int number=console.nextInt();
                if(number==0){
                    break;
                }
                sum+=number;
                count++;
            }
            System.out.printf("平均 %.2f%n",sum/count);
        }catch (InputMismatchException ex){
            System.out.printf("必须输入整数");
        }

    }
}